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Old 08-15-2018, 10:41 PM   #1
USDMSubii
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Default AF Correction 1 help!?

ok so i was able to get the P0171 to go away, but my af correction 1 is -25/+25 when driving, the actual number when driving stays at 0 if im idleing it goes like -8/+17 , im a total noob at what these numbers mean, im stumped is this normal? im not getting any codes or cel, and i cleaned the injectors,
checked the turbo inlet couldn’t find any cracks or holes, and cleaned my maf also just installed a AEM short ram( took away my P0171 code)

can the master gurus of NASIOC help me!!
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Old 08-16-2018, 12:10 AM   #2
USDMSubii
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Old 08-17-2018, 04:53 PM   #3
cmiovino
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Yikes, lots of "what the hell are you doing" going on here. Let's back up.

Number one, you have an Accessport, so which map are you running? This will tell us which intake you need to have on the car. If it's any OTS map from Cobb, you either need the Cobb SF or stock intake. The AEM one will not work.

The fact that you had a "too lean" code and yet you installed an AEM short ram to make it magically go away is mind boggling. It might have worked for some odd reason, possibly randomly throwing the metered air in another direction or playing with ECU values from the MAF, but either way it's most likely not the one you need. However, please correct me if you had this car professionally tuned for the AEM intake.

Next, AF correction numbers are more of a fine tuning ECU parameter. AF learning is what you want to be looking at. AF learning 1 is what is applied at that situation, but you can scroll through A, B, C, and D to see what the stored values in those MAF/airflow ranges are. Most likely they're all positive and one or more is pegged at 15%.

At that point, boost leak check the system... professionally. You can create your own and use an air compressor and check to see if it holds a certain pressure, but a shop can answer this for you much quicker for $40.

Track down the leak, if any, and fix. If there's no leak, it's most likely a sensor. You don't state your vehicle or have your profile filled out, but if it's up around 75-100k miles, swapping out both the front O2 sensor and MAF sensor are basic maintenance. Mine were completely shot around 115k and throwing the values off, but not enough for a CEL. Sensors can also just magically go bad after a few years too.

After all that, if you still have 15% positive AF learning going on, it's time to take it to a professional and let them sort it out.
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Old 08-17-2018, 05:00 PM   #4
86Dreams
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what that guy said as all true and you should listen to him.

But to directly answer the af correction 1 question: you dont need to worry about it, its completely normal for it to be all over the place.
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Old 08-18-2018, 07:39 AM   #5
USDMSubii
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hey, im running the stage 1 map, i wasnt aware you needed the AEM tuned!? can you do this with the V3 ( is there a map setting/custom intake)? i am replacing my 02 sensor tomorrow here, i replaced the maf sensor when i put on the AEM, the mind set behind the taking away of the p0171 code, i did a bit of research said it could have been a intake leak, my previous air intake was trashed, rubber hosing was shot, so when i replaced it with the aem everything was sealed, and it magically worked , dont ask how. i just bought a ancillary kit and replacing all vacuum lines, i simply want to know what is normal reading for that year thanks
btw its a 2002 wrx impreza got about 177miles on it engine was rebuilt at 160miles, runs fine just scared of it blowing up lol
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Old 08-18-2018, 11:02 AM   #6
86Dreams
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To be brutally honest it sounds like you're in over your head. If you're going to modify and tune the car yourself you need to be meticulous and methodical.

If you want people here to take the time to help you then you need to be very clear and explicit about what you have, when you made modifications and when you observed changes in performance.

The easiest thing for you to do is go to a pro tuner and tell them what's up and what you want. If not start by getting fuel injection systems by Kramer and Hoffman and reading it cover to cover. Then get a wide band o2 sensor and gauge and get it hooked up to a laptop and start logging so you can calibrate the MAF sensor to the intake.
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Old 08-18-2018, 03:56 PM   #7
USDMSubii
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@86Dreams, over my head? i just read that big thread where the guy ended up getting a rod knock, but then also read from numerous people people, “ 2002 dont need a tune for a short ram intake especially a AEM, saying that the 02-03 are safe.
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Old 08-18-2018, 08:10 PM   #8
cmiovino
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Eh, the '02-03 posts about "it doesn't need tuned" are only partially true. Some of it might just misinformation too.

Yes, people do say with the 2002 WRX you could run any intake and also a downpipe with no issues. You certainly won't be making any gains from it, but more importantly I believe it's only marginally 'safer'. Meaning, you probably won't throw a CEL immediately and the ECU might be able to compensate for it.

Another theory is when these posts were written, people were just running the SPT intake Subaru was selling, or people didn't know any better. We know today that you really do need a tune to be safe.

Either way, you certainly can't just run the Cobb OTS tune - read the notes. It specifically says either stock or Cobb SF intake. You'd make more power and be much safer if you just put the stock intake back on and ran the Cobb Stage 1 OTS tune.
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Old 08-19-2018, 01:24 AM   #9
86Dreams
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Quote:
Originally Posted by USDMSubii View Post
@86Dreams, over my head? i just read that big thread where the guy ended up getting a rod knock, but then also read from numerous people people, “ 2002 dont need a tune for a short ram intake especially a AEM, saying that the 02-03 are safe.
You're not going to learn this from forums. Can you say why they are saying that? Either through theory or experience?
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Old 08-19-2018, 05:30 AM   #10
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Quote:
Originally Posted by USDMSubii View Post
hey, im running the stage 1 map, i wasnt aware you needed the AEM tuned!? can you do this with the V3 ( is there a map setting/custom intake)? i am replacing my 02 sensor tomorrow here, i replaced the maf sensor when i put on the AEM, the mind set behind the taking away of the p0171 code, i did a bit of research said it could have been a intake leak, my previous air intake was trashed, rubber hosing was shot, so when i replaced it with the aem everything was sealed, and it magically worked , dont ask how. i just bought a ancillary kit and replacing all vacuum lines, i simply want to know what is normal reading for that year thanks
btw its a 2002 wrx impreza got about 177miles on it engine was rebuilt at 160miles, runs fine just scared of it blowing up lol
so if you have a p0171 what it is tellin you is that there is too much air coming into your engine and you are running lean. the Computer will compensate for the leaness but if it goes over a certain point, it will throw a code. So anyways. getting back to the code, it means that you have a leak somewhere between the maf and the heads. if you're af learing is still high, it means you havent fixed the problem. Go do a boost check and see where the leak is.

BTW where are you located
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Old 08-19-2018, 03:34 PM   #11
USDMSubii
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mf af learning sits a 0 -25/+25 while under load its -6/+14 this is what im seeing on the tuner, usually the number is all over the place, and im located in Canada
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Old 08-19-2018, 03:36 PM   #12
USDMSubii
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Default AF Correction 1 help!?

just bought the cobb sf intake ffs , that really pisses me off that i spent 900$ on a tuner and it can even ****in tune a short ram, just a money grab imo, for 400$ more you get to perfectly run fine with our piece of **** intake, such bs, people who made this tuner should be shot

Last edited by USDMSubii; 08-19-2018 at 03:42 PM.
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Old 08-19-2018, 06:07 PM   #13
Jersey Man10
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I thought you bought an AEM intake?
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Old 08-19-2018, 06:09 PM   #14
USDMSubii
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i did, but theres no tune for it , so out another 400$ for this cobb intake
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Old 08-19-2018, 06:14 PM   #15
Jersey Man10
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Then remove it and just run Stage 1 Tune.
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Old 08-19-2018, 06:26 PM   #16
USDMSubii
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remove the intake? i dont have the stock air intake
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Old 08-20-2018, 10:39 AM   #17
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Quote:
Originally Posted by USDMSubii View Post
just bought the cobb sf intake ffs , that really pisses me off that i spent 900$ on a tuner and it can even ****in tune a short ram, just a money grab imo, for 400$ more you get to perfectly run fine with our piece of **** intake, such bs, people who made this tuner should be shot
I get you're upset but Cobb is really clear about what their OTS tunes are designed for.
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Old 08-20-2018, 11:24 PM   #18
ColdSoda
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Quote:
Originally Posted by Wappit View Post
I get you're upset but Cobb is really clear about what their OTS tunes are designed for.
^ this.
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